Orthopedic alignment guide

ABSTRACT

Orthopedic guide, and methods of using the guide, for alignment of bone under fluoroscopic imaging. In an exemplary embodiment, the guide may include a radiopaque rod, a radiolucent carrier, and a radiopaque indicator held by the carrier. The rod and the indicator may be parallel to the same plane, and may form an angle between one another of less than 90 degrees when projected orthogonally onto the plane. The rod may be configured to be aligned with an axis defined by one or more bones of the leg, and the indicator aligned with a joint of the leg, in an anterior-posterior, fluoroscopic view of the leg. The angle formed between the rod and the indicator may correspond to an anatomic orientation of the axis and the joint relative to one another in a frontal plane of the leg.

INTRODUCTION

The knee joint is formed at the junction of the femur (thigh bone),tibia (shin bone), and patella (knee cap). Trauma to the leg canfracture the femur distally near the knee joint. If the femur isfractured sufficiently, the bone may need to be fixed surgically forstabilization and to encourage osteosynthesis.

A distally fractured femur may be fixed with a spanning member, such asa bone plate mounted on the lateral side of the bone. However, restoringthe knee joint accurately to its pre-fracture position before fixationcan be challenging. If the femur is not fixed properly, the knee jointmay be loaded asymmetrically when the leg bears weight, which can damagethe joint and promote development of arthritis.

SUMMARY

The present disclosure provides an orthopedic guide, and methods ofusing the guide, for alignment of bone under fluoroscopic imaging. In anexemplary embodiment, the guide may include a radiopaque rod, aradiolucent carrier, and a radiopaque indicator held by the carrier. Therod and the indicator may be parallel to the same plane, and may form anangle between one another of less than 90 degrees when projectedorthogonally onto the plane. The rod may be configured to be alignedwith an axis defined by one or more bones of the leg, and the indicatoraligned with a joint of the leg, in an anterior-posterior, fluoroscopicview of the leg. The angle formed between the rod and the indicator maycorrespond to an anatomic orientation of the axis and the joint relativeto one another in a frontal plane of the leg.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view of an exemplary bone fixation system including anorthopedic guide for properly orienting the tibiofemoral joint of theknee with respect to an anatomic axis of the femur, to align pieces ofthe femur with one another, and a bone fixation assembly (shownexploded) for fixing the aligned femur, with the bone fixation assemblyincluding a spanning member and fasteners therefor, in accordance withaspects of the present disclosure.

FIG. 2 is a fragmentary view of the guide of FIG. 1, taken normal to theflat sides of a transverse member of the guide.

FIG. 3 is another fragmentary view of the guide of FIG. 1, taken as inFIG. 2, but with the guide turned over such that the opposite flat sideof the transverse member is visible.

FIG. 4 is still another fragmentary view of the guide of FIG. 1, takengenerally along line 4-4 of FIG. 3 toward an end of the transversemember.

FIG. 5 is an end view of the guide of FIG. 1, taken generally along line5-5 of FIG. 3 toward a lateral side of the transverse member.

FIG. 6 is a fragmentary exploded view of the guide of FIG. 1.

FIG. 7 is a fluoroscopic view of the guide of FIG. 1 located on theright leg of a subject, with a radiopaque axial member of the guidealigned with an anatomic axis defined by the subject's right femur, andwith a radiopaque indicator of the guide aligned with a line defined bya tibiofemoral joint of the subject, taken during or after performanceof a method of bone alignment.

FIG. 8 is a magnified, fluoroscopic view of the guide and right leg ofFIG. 7, taken generally as in FIG. 7 around the subject's knee joint andillustrating (in-phantom) adjustment of the orientation of the subject'sknee joint relative to the anatomic axis of the femur in a frontal planeof the subject.

FIG. 9 is a view of the knee joint of FIG. 8, taken after fixation ofthe femur with the fixation assembly of FIG. 1, to hold the femur inalignment and the knee joint in an anatomic orientation while the femurheals.

FIG. 10 is a fluoroscopic, fragmentary view of the guide and right kneejoint of FIG. 8, taken with a line defined by the tibiofemoral joint ofthe knee joint arranged parallel to a central angle indicator of theguide.

FIG. 11 is a partially exploded view of an exemplary orthopedicalignment guide for properly orienting the tibiofemoral joint of theknee with respect to a mechanical axis of the leg defined by the femurand tibia, in accordance with aspects of the present disclosure.

FIG. 12 is a fragmentary view of the guide of FIG. 11, taken normal tothe opposite flat sides of the transverse member of the guide.

FIG. 13 is another fragmentary view of the guide of FIG. 11, taken as inFIG. 12 but with the guide turned over such that the other opposite flatside of the transverse member is visible.

FIG. 14 is a fluoroscopic fragmentary view of the guide of FIG. 11,taken as in FIG. 13 and showing radiopaque regions of the guide.

FIG. 15 is a fluoroscopic view of the guide of FIG. 11 located on theright leg of a subject, with a radiopaque axial member of the guidealigned with a mechanical axis defined by the subject's right femur andtibia, and with a radiopaque indicator of the guide aligned with a kneejoint of the subject, taken during or after performance of a method ofbone alignment.

FIG. 16 is a fragmentary view of another exemplary orthopedic alignmentguide, in accordance with aspects of the present disclosure.

FIG. 17 is a fragmentary view of the guide of FIG. 16, taken as in FIG.16 except viewed fluoroscopically to show radiopaque regions of theguide for alignment.

DETAILED DESCRIPTION

The present disclosure provides an orthopedic guide, and methods ofusing the guide, for alignment of bone under fluoroscopic imaging. In anexemplary embodiment, the guide may include a radiopaque rod, aradiolucent carrier, and a radiopaque indicator held by the carrier. Therod and the indicator may be parallel to the same plane, and may form anangle between one another of less than 90 degrees when projectedorthogonally onto the plane. The rod may be configured to be alignedwith an axis defined by one or more bones of the leg, and the indicatoraligned with a joint of the leg, in an anterior-posterior, fluoroscopicview of the leg. The angle formed between the rod and the indicator maycorrespond to an anatomic orientation of the axis and the joint relativeto one another in a frontal plane of the leg. The joint may be a naturaljoint, or a partially or totally prosthetic joint. For example, thejoint may be provided by a natural knee joint, a hemi-prosthetic kneejoint, or a fully prosthetic knee joint.

An exemplary method of bone alignment under fluoroscopic imaging isprovided. In the method, a guide may be selected. The guide may includea radiopaque axial member, a radiolucent carrier, and a radiopaqueindicator held by the carrier. The axial member and the indicator may beparallel to the same plane and may form an angle between one another ofless than 90 degrees when projected orthogonally onto the plane. Thecarrier may have a first side and a second side opposite one another.The axial member may be aligned with an axis defined by one or morebones of a leg, and the indicator aligned with a joint of the leg, in ananterior-posterior, fluoroscopic view of the leg. The first side of thecarrier may face the joint if the leg is a left leg, and the second sideof the carrier may face the joint if the leg is a right leg.

The guide disclosed herein facilitates alignment of a fractured/cutbone, and more particularly, alignment of pieces of the bone relative toone another, to restore the pieces to an anatomic orientation relativeto one another. This alignment of the bone may be accomplished byadjusting an orientation of a joint formed in part by the bone, and askeletal axis defined at least in part by the bone, relative to oneanother in a plane, such as an anatomic plane (e.g., a frontal plane)defined by the subject. The joint and the skeletal axis are consideredto have an “anatomic orientation” relative to one another when theirorientation substantially matches a typical, average, and/or acceptedrelative orientation for the joint and the axis found in a population towhich the subject belongs. The guide disclosed herein allows a surgeonto more accurately and reliably align pieces of a bone under fluoroscopyduring a fixation procedure, which may result in better restoration ofleg function and less joint degeneration long term.

The terms “radiopaque” and “radiolucent,” as used herein, are relativeterms that describe the efficiency with which x-rays are blocked. Astructure or material that is radiopaque blocks passage of x-rayssubstantially more efficiently than a structure or material that isradiolucent. Thus, a radiopaque structure is visible by x-ray imaging,even when overlapped completely in the field of view by a largerradiolucent structure, which may or may not be visible by x-ray imaging.

Further aspects of the present disclosure are described in the followingsections: (I) bone fixation system with an orthopedic alignment guide,(II) methods of bone alignment and/or confirming bone alignment, and(III) examples.

I. BONE FIXATION SYSTEM WITH AN ORTHOPEDIC ALIGNMENT GUIDE

This section provides an overview of an exemplary bone fixation system30 including a fixation assembly 40 to fix a bone, and afluoroscopically-visible alignment guide 50 to aid restoring and/orconfirming proper alignment of a fractured/cut bone, and thus ananatomic orientation between an axis defined at least in part by thebone and a joint formed in part by the bone; see FIGS. 1-10.

FIG. 1 shows exemplary components of fixation system 30. Fixationassembly 40 may include at least one spanning member 60 (interchangeablytermed a fixation device) to bridge at least one discontinuity (abreak/cut) in the bone, and one or more fasteners 62 to attach thespanning member to bone on opposite sides of the discontinuity. Thespanning member is shown here somewhat schematically with a planarshape, but may be shaped during manufacture and/or intraoperatively tofollow the contours of a surface region of bone that will be covered bythe spanning member. More generally, the spanning member may beconfigured to be placed on the bone and/or in the bone to stabilize thebone and restrict movement of pieces of the bone relative to oneanother. Accordingly, the spanning member may, for example, include abone plate, an intramedullary nail, a fastener (e.g., a screw, pin,wire, etc.), or the like. Separate fasteners 62 may be omitted if thespanning member fastens itself to bone.

Guide 50 may be configured for use with a limb, namely, an arm or a leg.The guide may be designed for use with only a left limb or only a rightlimb, or for both left and right limbs. In the depicted embodiment,guide 50 is configured to be used alternatively for alignment of afractured/cut left femur and alignment of a fractured/cut right femur,but in other embodiments may be configured for alignment of afractured/cut left/right tibia, left/right humerus, left/right ulna,left/right radius, or the like. The guide provides afluoroscopically-visible template to aid alignment of bone pieces (e.g.,as a fracture is reduced and/or during an osteotomy procedure to changebone shape), and/or during/after installation of spanning member 60. Thetemplate allows the surgeon to compare the current orientation of ajoint formed in part by the bone, with a desired, anatomic orientationthereof. Thus, the guide may provide a reference that helps a surgeon toproperly restore, and/or to confirm a restored orientation of, thejoint.

Guide 50 may have an axial member 64 and a transverse member 66 (seeFIGS. 1-6). Each of members 64, 66 may be formed at least partially of aradiopaque material, such as metal, that blocks transmission of X-rayssubstantially more efficiently than bone, to provide a visible contrastwith bone in x-ray images. Each of members 64, 66 may define arespective axis 68, 70 with radiopaque material thereof, and atransverse member 68 (and/or a radiolucent portion thereof) may define aplane 72, which may be a central plane of the transverse member.

Axes 68, 70 (and/or the corresponding radiopaque structures of guide 50defining these axes) may be linear without projection and/or may belinear when projected orthogonally onto plane 72. The axes (and/or thecorresponding radiopaque structures) may lie in parallel planes or thesame plane, and each may be parallel to plane 72. The axes (and/or thecorresponding radiopaque structures) may form any suitable angle(s) (θ)between one another when projected orthogonally onto plane 72 (see FIGS.2, 3, and 10). The angle(s) may be less than 90 degrees, greater than 90degrees, 90 degrees, or a combination thereof (e.g., defining a pair ofsupplementary angles (having a sum of 180 degrees), neither of which is90 degrees). In some embodiments, the axes (and/or the correspondingradiopaque structures) may form an angle between one another of 78-89,79-89, 78-88, 79-88, 78-84, 79-83, 80-82, 79, 80, 81, 82, 85-89, 85-88,86-88, 87-89, 86, 87, 88, or 89 degrees, among others, when projectedorthogonally onto plane 72. The angle may represent an anatomicorientation of a natural/prosthetic joint-of-interest of the skeleton,relative to an axis defined by one or more bones of the skeleton, in aselected plane of the skeleton, as described further below.

Axial member 64 may have any suitable structure and properties. Theaxial member may be linear and elongated parallel to axis 68, and maydefine a long axis of guide 50 that is coincident with axis 68. Axialmember 64 may be connected to transverse member 66, such as attached(e.g., firmly) to prevent axial motion of members 64, 66 relative to oneanother parallel to the long axis of the guide, and/or slidably coupledto permit this axial motion. If slidably coupled, transverse member 66may or may not be permitted to rotate about axis 68. If the transversemember is rotatable, axes 68, 70 may maintain the angular relationshipdescribed above.

The axial member may be solid or hollow (e.g., cannulated), and may be asingle piece (i.e., monolithic), or two or more pieces, which may bepermanently or removably attached to one another. In some embodiments,axial member 64 may be mostly or entirely radiopaque, such that theaxial member contrasts with bone when imaged with x-rays. The axialmember may be described as a rod 74, which may have any suitablecross-sectional shape, such as circular, oval, polygonal (e.g.,rectangular), or the like. Rod 74 may have a substantially uniform orvarying cross-sectional shape and/or cross-sectional size along itslength.

Axial member 64 (and/or guide 50) may have any suitable length, based onthe type of limb and the particular skeletally-defined axis to bealigned with the axial member, as described in more detail below. Forexample, the axial member (and/or the guide) may have a length of atleast about 20, 25, 30, 40, 50, 75, or 100 centimeters, among others.Alternatively, or in addition, the axial member may be longer than, orshorter than, a long bone (e.g., the femur and/or tibia) of an averageadult human leg, or a long bone (i.e., the humerus, ulna, and/or radius)of an average adult human arm. In some embodiments, the axial member maybe longer than the human leg or human arm, as measured from the hipjoint to the ankle joint or from the shoulder joint to the wrist joint.

Transverse member 66 may include a radiolucent carrier 76 and one ormore elongated, radiopaque indicators 78, which may be held by thecarrier (see FIGS. 1 and 6). Carrier 76 may be elongated transverse toaxis 68 of axial member 64, optionally parallel to axis 70 defined byone of indicators 78. The carrier may be formed of any suitableradiolucent material, such as polymer or carbon-fiber reinforcedpolymer, among others.

Carrier 76 may have a pair of sides 80, 82 (interchangeably calledsurfaces) that are opposite from, and, optionally, parallel to, oneanother (see FIGS. 2, 3, and 5). Each side 80, 82 may be flat andparallel to axial member 64, indicator 70, and/or plane 72. The sameguide may be used for alignment with a left limb and a right limb byswitching the side 80 or 82 that faces the limb, and particularly thejoint-of-interest thereof. In other words, the guide can be turned overto make it suitable for alternative use with a left limb and a rightlimb. In the depicted embodiment, side 80 faces away from the right kneewhen the guide is used for the right femur, and side 82 faces away fromthe left knee when the guide is used for the left femur.

Transverse member 66 and/or another portion(s) of the guide may havevarious indicia 84 to facilitate proper use of the guide (see FIGS.1-3). The indicia may be visible on sides 80, 82 and/or other surfacesof carrier 76, and each may be formed at a surface of the carrier.Exemplary indicia may include orientation indicia to inform the surgeonas to which sides 80, 82 should face toward and away from a left boneversus a right bone. The orientation indicia may include characters orother symbols configured to convey the concepts of left and right and/ormedial and lateral to the surgeon. For example, in the depictedembodiment, side 80 is marked with the word “right” and faces away fromthe right leg (and is thus visible to the surgeon) when the guide isused properly for alignment of the right leg (see FIG. 2). Similarly,side 82 is marked with the word “left” and faces away from the left legwhen the guide is used properly for alignment of the right leg (see FIG.3). Also or alternatively, opposite ends of transverse member 66 may bemarked with characters or other symbols representing lateral and medial,such as the characters “L” and “M” in the depicted embodiment (see FIGS.2 and 3). When the guide is used properly for a left leg and a rightleg, the same end of the transverse member points laterally, and thesame opposite end of the transverse member points medially. Otherindicia 84 may convey the bone (e.g., “femoral”) to be aligned with theguide, and/or an indication of whether the skeletal axis for alignmentis anatomic or mechanical (e.g., “anatomic axis”). The indicia also oralternatively may include axial and transverse marks 86 a-86 dcorresponding to axes defined by radiopaque structures of the guide,which may be internal (also see FIG. 6), and/or characters indicatingthe value for angle θ (e.g., “81” degrees near mark 86 b) and/or anangular offset value (e.g., “10” degrees) from angle θ near marks 86 c,86 d.

Carrier 76 may define an opening 87 to receive a portion of axial member64 (see FIGS. 1 and 5). For example, in the depicted embodiment, an endof the axial member is received in opening 87 and firmly attached to thecarrier at the opening, such as by a press-fit, bonding, a fastener, orthe like. The opening may be sized in correspondence with the diameterof the axial member.

FIGS. 4-6 show an exemplary two-piece structure for carrier 76. Thecarrier may include a base 88 and a cover 90 that are attached to oneanother. For example, a top surface of base 88 may be bonded to a bottomsurface of cover 90. The base and cover may have a different thicknessrelative to one another, as shown, or the same thickness.

FIG. 6 shows exemplary radiopaque indicators 78 (interchangeably calledreferences) of transverse member 66. The indicators may include aprimary indicator 92 (e.g., a central indicator) to define axis 70, oneor more offset indicators 94 (corresponding to surface marks 86 c, 86 d;see FIG. 2), and one or more skew indicators 96. Each indicator may beelongated, and may be formed of a thin radiopaque member, such as awire. The indicator may be formed of metal. The diameters and/or lengthsof indicators 92, 94 may be the same as one another or different. Forexample, central indicator 92 may have a greater diameter and/or lengththan offset indicators 94, to help focus the surgeon's attention on thecentral indicator.

Indicators 92, 94 may be substantially coplanar with one another andparallel to plane 72. Offset indicators 94 may be uniformly offset fromcentral indicator 92 in opposite rotational directions, at least whenprojected orthogonally onto plane 72. The offset may be a whole numberof one or more degrees, such as 1, 2, 3, 5, or 10 degrees, among others.

Skew indicators 96 each may be arranged orthogonally to plane 72. Theskew indicators, when x-ray imaged, generate image marks that indicatewhether and how much axes 68, 70 and plane 72 are skewed from orthogonalto the x-ray irradiation axis (the x-ray beam axis) used for imaging.The image marks may be non-elongated (e.g., circular) when no skew ispresent (e.g., see FIG. 8), and become increasingly elongated withincreasing skew. The orientation of the elongated marks in x-ray imagescorresponds to the direction of skew.

Each indicator 78 may be located at least partially inside carrier 76. Amajority of the indicator may be located inside the carrier, and,optionally, the indicator may be substantially enclosed by the carrier.In the depicted embodiment, primary indicator 92 and offset indicators94 are located in depressions 98 defined by the base of the carrier,with the depressions forming by milling, cutting, molding, or the like.Also, skew indicators 96 are located in holes 100 arranged orthogonallyto plane 72 of the carrier. Each indicator 78 may or may not be firmlyattached to the carrier, such as with an adhesive, and may or may not beremovable therefrom. In other embodiments, one or more of the indicatorsmay be embedded in the carrier as the carrier is being formed (e.g.,molded), attached to the exterior of the carrier, formed in situ by orfrom a planar layer of material (such as by cutting or materialdeposition), or a combination thereof, among others.

FIG. 7 schematically shows an x-ray image created as a fluoroscopic,anterior-posterior view of a right leg 102 of a subject, with guide 50operatively disposed on an anterior side of the subject's right thigh,on soft tissue 104 thereof. Radiopaque portions of the guide,particularly axial member 64 and indicators 92, 94, form black linessuperimposed on the subject's skeleton. Axial member 64 is parallel toan anatomic axis of the subject's right femur 106. (The anatomic axismay be defined by a straight line centered on the shaft of femur 106.)Transverse member 66 (particularly indicators 92, 94) is positioned overtibiofemoral joint 108 of the right leg, where femur 106 and tibia 110articulate with one another. (The tibiofemoral joint is part of the kneejoint.) Primary indicator 92 is parallel to a line defined by joint 108,such as a line tangent to natural/artificial femoral condyles of femur106. The femur has sustained a fracture 112, which has damaged the bonesufficiently (e.g., by comminution) to make accurate fracture reductiondifficult without guide 50.

In other embodiments, guide 50 may be configured to be used for afractured/cut tibia 110. Axial member 64 may be arranged on the leg toextend distally from tibiofemoral joint 108 and aligned with an anatomicaxis defined by the tibia in x-ray images. The angle θ defined by axes68, 70 may be about 86-88 degrees, which corresponds to the anatomicorientation of joint 108 with respect to the tibial anatomic axis (orthe mechanical axis defined by the femur and tibia).

FIG. 8 shows a magnified, more fragmentary view of the image of FIG. 7,taken around tibiofemoral joint 108 and illustrating (in-phantom)adjustment, indicated by arrows at 114, of the orientation of the jointin a frontal plane of the subject. The adjustment changes theorientation of pieces of femur 106 relative to one another, namely, theorientation of a distal femoral fragment 116 (and the rest of right leg102 distal to joint 108) with respect to a shaft 118 of the femur.Adjustment of the orientation of the femoral pieces may be performed toplace joint 108 in an anatomic orientation in the frontal plane, tomatch the orientation to an average, optimal, accepted, and/or desiredorientation for the joint. Patella 120 also is shown for clarity.

Skew indicators 96 are visible as non-elongated dots, indicating thatthe X-ray irradiation axis is parallel to the long axis of eachindicator 96. In other words, the irradiation axis is orthogonal axialmember 64 and indicator 70, and thus orthogonal to plane 72 defined bytransverse member 66 of guide, indicating a complete absence ofdetectable skew.

FIG. 9 shows femur 106 fixed with fixation assembly 40, which holdsfemur 106 in an aligned configuration while the femur heals.

FIG. 10 shows a simplified, more fragmentary view of the x-ray image ofFIG. 7, taken generally as in FIG. 8, but with tibia 110 and femoralshaft 118 omitted. Femoral condyles 122 of the knee joint are alignedwith primary indicator 92. More particularly, a line tangent to bothcondyles 122 is parallel to the primary indicator. Offset indicators 94are each offset by a defined amount (here, ten degrees) in oppositerotational directions from primary indicator 92, and allow a surgeon toestimate how much the orientation of pieces of the femur (or other bone)needs to be adjusted to place the joint parallel to primary indicator92, and/or to estimate the angle by which the joint is offset from ananatomic orientation, before or after installation of a fixation device.

II. METHODS OF BONE ALIGNMENT AND/OR CONFIRMING BONE ALIGNMENT

This section describes exemplary methods of aligning pieces of afractured/cut bone, or confirming their alignment, to ensure that anaxis defined at least in part by the bone and a joint associated withthe bone are in an anatomic orientation relative to one another. Themethod steps described in this section may be performed in any suitableorder and combination, using any of the devices (guides, spanningmembers, fasteners, etc.), and any suitable combination of devicefeatures, of the present disclosure.

Any of the method steps may be performed with the aid of x-ray imaging,particularly fluoroscopy. X-ray imaging is any imaging technique thatutilizes x-rays to view one or more objects, such as one or more bonesof a subject's skeleton and/or radiopaque regions of an orthopedicalignment guide, among others. The object(s) may be irradiated with abeam of x-rays, and the distribution of x-rays that pass through theobject is detected directly or indirectly, with an imaging instrument,to create x-ray images. The x-ray images may or may not be recorded(i.e., saved). Detection may, for example, be performed by inducingemission of light with the x-rays. Accordingly, the imaging instrumentmay be a fluoroscope including a fluorescent screen to createfluoroscopic x-ray images in real time. An exemplary fluoroscope thatmay be suitable is a C-arm. In other embodiments, the imaging instrumentmay create radiographic x-ray images, which may be digital images.

A limb of a subject may be selected. The limb may be an arm or a leg,and the subject may be from any suitable vertebrate species, such ashuman. The limb may include a bone, which may be completely natural orpartially prosthetic (e.g., including a prosthesis that replaces a jointsurface(s) of the bone). The bone may have at least one discontinuity (afracture/cut), which may divide the bone into two or more pieces, and/ormay include a bone that is cut into two or more pieces intraoperativelyin an osteotomy procedure. The bone may be a long bone, such as a femur,tibia, fibula, humerus, radius, or ulna, among others.

A guide may be selected for use in the method. The selected guide mayhave any suitable combination of features of the present disclosure. Forexample, the same guide may be configured for use with a left limb and aright limb, with the working positions of the guide for the left andright limbs being related to one another, in part, by turning the guideover. The guide may include radiopaque structures that define an angle θcorresponding to an anatomic orientation of a skeletal axis and a jointrelative to one another, as described elsewhere herein.

The guide and at least a portion of the selected limb may be disposed inthe field of view of the imaging instrument, by moving the guide, limb,and imaging instrument relative to one another. At least one joint ofthe limb may be located in the field of view. The joint may be a hipjoint, a knee joint (and/or tibiofemoral joint), and/or an ankle(talocrural) joint, if the limb is a leg; or a shoulder joint, an elbowjoint, and/or a wrist joint, if the limb is an arm. The joint may benatural or at least partially prosthetic. For example, the joint may bea natural knee joint, a hemi-prosthetic knee joint, or a fullyprosthetic knee joint. A hemi-prosthetic knee joint may include aprosthetic femoral component that articulates with a natural tibia, or aprosthetic tibial component that articulates with a natural femur, amongothers.

A skeletal portion of the limb also may be located in the field of view.The skeletal portion may define an axis of the subject's skeleton. Thedefined axis may be a linear anatomic axis, which may be defined by ashaft of a bone and/or a feature(s) at one or both ends of the bone.Alternatively, the defined axis may be a linear mechanical axis, whichmay be defined by a pair of joints of the limb. For the leg, themechanical axis may be defined by a straight line extending from the hipjoint (e.g., the center of the femoral head) to the center of the anklejoint. For the arm, the mechanical axis may be defined by a straightline extending from the shoulder joint (e.g., the center of the humeralhead) to the center of the wrist joint.

The field of view may be created by any suitable orientation of the beamof x-rays of the imaging instrument with respect to the limb and theguide. For example, the beam may propagate along an anterior-posterioraxis of the limb, and in an anterior-to-posterior orposterior-to-anterior direction, for an anterior-posterior view andanterior-posterior images. As another example, the beam may propagatealong a medial-lateral axis of the limb (from medial to lateral orlateral to medial) for medial-lateral images. The beam may define anirradiation axis that is orthogonal to long axes defined by an axialmember (e.g., a rod) and one or more indicators of the guide, and/orparallel to skew indicators of the guide.

The guide may be located on and overlapping with the limb in the fieldof view, and optionally in direct contact with the limb. The guide maybe placed on any suitable side of the limb, such as the anterior,posterior, medial, or lateral side of the limb. The transverse member ofthe guide, and particularly radiopaque indicators thereof, may bepositioned to overlap, in x-ray images, the joint-of-interest for whichan orientation is being assessed and/or adjusted. More particularly, anindicator of the guide may be arranged roughly parallel to a linedefined by the joint-of-interest in x-ray images of the limb (e.g., in afluoroscopic view of the limb). The line may be defined by anatural/artificial end portion of a bone of the joint-of-interest, suchas condyles or plateaus formed by the end of the bone. In someembodiments, the line may be defined partially or completely by aprosthetic structure, which may or may not be formed of metal and/orradiopaque. For example, the line may be defined by a prosthetic femoralportion or a prosthetic tibial portion of a knee joint in a fluoroscopicview of the joint. In some embodiments, the line may be defined by abase of a prosthetic portion of a knee joint. The bone may be fracturedafter installation of a prosthetic joint or prosthetic portion of thejoint, for example, months or years later.

Radiopaque structures of the guide may be aligned with fluoroscopicallyvisible features of the limb. Alignment may be performed by any suitablemovement of the guide, the limb, and/or portions of the limb, relativeto one another, and in any suitable order. A radiopaque axial member ofthe guide may be aligned with an axis defined by the subject's skeleton,such as a linear anatomic axis or a linear mechanical axis defined byone or more bones of the selected limb in the images. When aligned, thelong axis of the axial member and the axis defined by one or more bonesof the skeleton may be parallel to one another, and may be substantiallycoincident with one another, in one or more x-ray images created by theimaging instrument. A radiopaque indicator of the guide may be alignedwith a joint of the limb, particularly a line defined by the joint, asdescribed above. When aligned, the indicator may be parallel to theline, and an axis defined by the indicator may be substantiallycoincident with the line, in fluoroscopic images.

The step of aligning may include adjusting an orientation of the axisand the joint-of-interest relative to one another by moving pieces ofthe fractured/cut bone of the selected limb relative to one another in aplane. The orientation may be adjusted with the aid of fluoroscopicimages created by the imaging instrument. More particularly, a portionof the limb may be moved, and the alignment of (i) a line defined by thejoint-of-interest and (ii) an indicator of the guide may be observedfluoroscopically, during or after movement, until the line and indicatorare parallel to one another. Pieces of the bone may be moved relative toone another in a plane that is transverse to the beam of x-rays used forimaging, such as orthogonal to the beam. The plane may be a frontalplane (i.e., a plane orthogonal to an anterior-posterior axis of thelimb), a sagittal plane (i.e., a plane orthogonal to a medial-lateralaxis of the limb), or the like.

The broken/cut bone may be fixed to substantially immobilize pieces ofthe bone relative to one another. Fixation may be performed after thebone has been aligned, or the alignment of the bone may be assessed withthe guide after the bone has been fixed, to confirm that the bone issufficiently aligned.

III. EXAMPLES

The following examples describe selected aspects and embodiments of thepresent disclosure including exemplary orthopedic alignment guides, andmethods of using the guides for alignment and/or assessing alignment.The aspects and features of the guides and methods described in each ofthese examples may be combined with one another and with aspects andfeatures of the systems, devices, and methods described elsewhere in thepresent disclosure, in any suitable combination. These examples areintended for illustration and should not limit the entire scope of thepresent disclosure.

Example 1. Orthopedic Alignment Guide for a Mechanical Axis of aSkeleton

This example describes an exemplary orthopedic alignment guide 150having an axial member 64 configured to be arranged parallel to a linearmechanical axis defined by bones of a skeleton; see FIGS. 11-15.

FIG. 11 shows a partially exploded view of guide 150. The guide may bestructured generally as described above in Section I for guide 50, andmay have any suitable combination of elements and features disclosedelsewhere herein. For example, guide 150 includes an axial member 64 anda transverse member 66.

Axial member 64 of guide 150 may be significantly longer than thecorresponding axial member of guide 50, to facilitate aligning the axialmember of guide 150 with a mechanical axis defined by a pair of movablejoints of the skeleton, such as the hip joint and the ankle joint of aleft or right leg (see below). To span the distance between the pair ofjoints, the axial member may be at least twice as long as in guide 50,such as at least the length of an average human leg (e.g., at leastabout 60, 70, 80, 90, or 100 centimeters, among others). The axialmember may have a fixed or adjustable length. Accordingly, the axialmember may include two or more longitudinal sections, such as rodsections 162 a, 162 b, 162 c that are removably connectable to oneanother end-to-end. In the depicted embodiment, the rod sections areconnectable to one another via threaded connections 164 a, 164 b eachincluding an external thread 166 defined by one rod section and aninternal thread defined by a sleeve 168 of an adjacent rod section.

Transverse member 66 may be configured to be slidable along axial member64, parallel to the long axis thereof, indicated by a double-headedmotion arrow at 170. Friction between members 64 and 66 may preventmember 66 from moving freely along axial member 64 and/or rotating aboutthe long axis of the axial member, to resist undesired movement oftransverse member 66 during use. Alternatively, or in addition, theguide may include a locking member, such as a set screw or detent, thatcan be manipulated to adjust the transverse member between movable andfixed configurations.

Members 64, 66 may define respective axes 68, 70 as described above (seeFIGS. 11-13). However, an angle (θ) defined between the axes may bedifferent than in guide 50, such as 86-88 degrees, among others, tomatch the average, accepted, and/or desired orientation of thetibiofemoral joint with respect to a mechanical axis of the leg. Forexample, in the depicted embodiment, angle θ is 87 degrees (see FIGS. 12and 13), which is indicated on both sides 80, 82 of transverse member 66by numeric characters.

FIG. 14 shows a schematic x-ray image representing a fluoroscopic viewof guide 150 that corresponds to FIG. 13. Transverse member 66 maycontain radiopaque indicators 78, as described above for guide 50. Theindicators may include primary indicator 92, offset indicators 94, andskew indicators 96.

FIG. 15 schematically shows a fluoroscopic image of guide 150 on rightleg 102 of a subject, viewed along an anterior-posterior axis, withtibiofemoral joint 108 in an anatomic orientation. The axis defined byaxial member 64 is aligned with a linear mechanical axis defined by astraight line extending from hip joint 172 to ankle joint 174 of theright leg in the image. More particularly, the axis defined by axialmember 64 extends substantially through the center of femoral head 176of hip joint 172 and through the center of ankle joint 174. One end ofthe axial member is positioned near the ankle joint, and the transversemember may be moved by the surgeon along the axial member, if needed, toposition the transverse member over the knee joint. Transverse member 66is superimposed on tibiofemoral joint 108, with primary indicator 92parallel to a line tangential to the femoral condyles of the joint. Toreach this configuration, the surgeon may rotate the lower leg in thefrontal plane and in the appropriate direction, under fluoroscopicimaging, until the mechanical axis of the leg and the line defined byjoint 108 form an angle of 87 degrees, as measured with guide 150. Guide150 alternatively may be used by aligning axial member 64 with theanatomic axis of the tibia, because the anatomic orientation of thetibiofemoral joint with respect to either the mechanical axis of theleg, or the anatomic axis of the tibia, is the same (about 87 degrees).

Example 2. Joint Alignment Guide with Protractor

This example describes an exemplary orthopedic alignment guide 250forming a protractor 252; see FIGS. 16 and 17.

Guide 250 may be structured generally as described above in Section Ifor guide 50 and/or guide 150 of Example 1, and may have any suitablecombination of elements and features disclosed elsewhere herein. Forexample, axial member 64 of guide 250 may be configured to be alignedwith an anatomic axis or a mechanical axis of a leg or arm, amongothers. However, guide 250 may form an angle (θ) of 90 degrees betweenaxes 68, 70 defined respectively by axial member 64 and primaryindicator 92 of transverse member 66, when the axes are projectedorthogonally onto a plane. The primary indicator is marked as “0” on theguide. Offset indicators 94 may be offset uniformly from primaryindicator 92 and one another, and by an integral number of degrees(e.g., 1, 2, 3, 4, or 5 degrees, among others), to form a protractor. Inthe depicted embodiment, the indicators are uniformly separated by fivedegrees from one another.

The surgeon may rely on interpolation, if needed, to place a joint at ananatomic orientation, based on reference to the indicators. For example,if the surgeon wants to orient a tibiofemoral joint at 81 degrees withrespect the anatomic axis of the femur, guide 250 can be used generallyas described above for guide 50. However, rather than aligning the jointwith primary indicator 92, the surgeon adjusts the femur until thetibiofemoral joint is approximately nine degrees in the appropriaterotational direction from primary indicator 92, as judged by comparisonwith offset indicators 94, which are labeled as “5” and “10” degreesoffset from the primary indicator.

Example 3. Selected Embodiments

This example describes selected embodiments of an orthopedic alignmentguide and methods of using the guide to align and/or confirm alignmentof bone. The selected embodiments are presented as a series of numberedparagraphs.

Paragraph 1. A method of bone alignment under fluoroscopic imaging, themethod comprising: (A) selecting a guide including a radiopaque axialmember, a radiolucent carrier, and a radiopaque indicator held by thecarrier, wherein the axial member and the indicator are parallel to thesame plane and form an angle between one another of less than 90 degreeswhen projected orthogonally onto the plane, and wherein the carrier hasa first side and a second side opposite one another; and (B) aligningthe axial member with an axis defined by one or more bones of a leg, andthe indicator with a joint of the leg, in an anterior-posterior,fluoroscopic view of the leg; wherein the first side of the carrierfaces the joint if the leg is a left leg, and the second side of thecarrier faces the joint if the leg is a right leg.

Paragraph 2. The method of paragraph 1, wherein the axial member and theindicator form an angle between one another of 79 to 88 degrees whenprojected orthogonally onto the plane.

Paragraph 3. The method of paragraph 1 or 2, wherein the indicator is acentral indicator, wherein the step of selecting a guide includes a stepof selecting a guide having a pair of radiopaque offset indicators, andwherein the offset indicators are offset in opposite rotationaldirections from the central indicator when the central indicator andeach of the offset indicators is projected orthogonally onto the plane.

Paragraph 4. The method of any of paragraphs 1 to 3, wherein each of theoffset indicators is offset by an integral number of degrees from thecentral indicator when the central indicator and the offset indicatorsare projected orthogonally onto the plane.

Paragraph 5. The method of any of paragraphs 1 to 4, wherein the step ofselecting a guide includes a step of selecting a guide having one ormore radiopaque skew indicators held by the carrier, and wherein eachskew indicator defines a long axis that is orthogonal to the plane.

Paragraph 6. The method of any of paragraphs 1 to 5, wherein the step ofselecting a guide includes a step of selecting a guide having theindicator substantially enclosed by the carrier.

Paragraph 7. The method of any of paragraphs 1 to 6, wherein the step ofselecting a guide includes a step of selecting a guide in which thefirst side and the second side of the carrier are parallel to the plane.

Paragraph 8. The method of any of paragraphs 1 to 7, wherein the step ofselecting a guide includes a step of selecting a guide havingorientation indicia indicating that the second side of the carriershould face away from the joint when the guide is used for a left leg,and that the first side of the carrier should face away from the jointwhen the guide is used for a right leg.

Paragraph 9. The method of any of paragraphs 1 to 8, wherein the step ofaligning includes a step of moving pieces of a femur or tibia relativeto one another.

Paragraph 10. The method of any of paragraphs 1 to 9, wherein the jointis a knee joint, and wherein the knee joint is natural or at partiallyprosthetic.

Paragraph 11. The method of any of paragraphs 1 to 10, wherein the stepof aligning includes a step of aligning the indicator with a linedefined by a femoral portion or a tibial portion of the knee joint inthe anterior-posterior, fluoroscopic view of the leg.

Paragraph 12. The method of any of paragraphs 1 to 11, wherein the axisis an anatomic axis defined by the femur or tibia of the leg.

Paragraph 13. The method of any of paragraphs 1 to 11, wherein the axisis a mechanical axis defined by the femur or tibia of the leg.

Paragraph 14. The method of any of paragraphs 1 to 13, furthercomprising a step of selecting one of the first and second sides of thecarrier to face the joint based on whether the leg is a left leg or aright leg.

Paragraph 15. The method of paragraph 14, wherein the step of selectingone of the first and second sides is based on orientation indiciapresented by the guide.

Paragraph 16. The method of paragraph 15, wherein the orientationindicia include a plurality of characters.

Paragraph 17. The method of any of paragraphs 1 to 16, wherein the stepof aligning includes a step of moving pieces of a femur or tibia of theleg relative to one another in a frontal plane of the subject while theguide and the leg are imaged fluoroscopically.

Paragraph 18. The method of any of paragraphs 1 to 17, furthercomprising a step of fixing the femur or the tibia with a bone fixationdevice after the step of aligning.

Paragraph 19. The method of any of paragraphs 1 to 18, furthercomprising a step of creating a fluoroscopic image in which the axialmember and the indicator are orthogonal to an irradiation axis of x-raysused for imaging.

Paragraph 20. The method of any of paragraphs 1 to 19, wherein the jointis the hip joint, the knee joint, or the ankle joint of the leg.

Paragraph 21. The method of any of paragraphs 1 to 20, performed withany of the guides described below in paragraphs 22 to 40 and/orelsewhere in the present disclosure.

Paragraph 22. A guide for bone alignment under fluoroscopic imaging,comprising: (A) a radiopaque rod; (B) a radiolucent carrier having afirst side and a second side opposite one another; and (C) a radiopaqueindicator held by the carrier; wherein the rod and the indicator areparallel to the same plane and form an angle between one another of lessthan 90 degrees when projected orthogonally onto the plane, wherein therod is configured to be aligned with an axis defined by one or morebones of a leg, and the indicator aligned with a joint of the leg, in ananterior-posterior, fluoroscopic view of the leg, and wherein the guideis configured to be used alternatively for a left leg with the firstside of the carrier facing the joint, and for a right leg with thesecond side of the carrier facing the joint.

Paragraph 23. The guide of paragraph 22, wherein the rod and theindicator form an angle between one another of 79 to 88 degrees whenprojected orthogonally onto the plane.

Paragraph 24. The guide of paragraph 22 or 23, wherein the guidecomprises orientation indicia to indicate that the second side of thecarrier should face away from the joint when the guide is used for theleft leg, and that the first side of the carrier should face away fromthe joint when the guide is used for the right leg.

Paragraph 25. The guide of any of paragraphs 22 to 24, wherein theindicator is a central indicator, wherein the guide further comprises apair of radiopaque offset indicators, and wherein the offset indicatorsare offset in opposite rotational directions from the central indicatorwhen the central indicator and the offset indicators are projectedorthogonally onto the plane.

Paragraph 26. The guide of any of paragraphs 22 to 25, wherein theindicator is substantially enclosed by the carrier.

Paragraph 27. The guide of any of paragraphs 22 to 26, wherein theindicator is configured to be aligned with a knee joint.

Paragraph 28. The guide of any of paragraphs 22 to 27, wherein the guidecomprises one or more radiopaque skew indicators each elongatedorthogonal to the plane.

Paragraph 29. The guide of any of paragraphs 22 to 28, wherein theindicator is located between pieces of the carrier that are bonded toone another.

Paragraph 30. The guide of any of paragraphs 22 to 29, wherein the jointis a hip joint or an ankle joint.

Paragraph 31. The guide of any of paragraphs 22 to 30, wherein the rodand the indicator form an angle between one another of 85 to 88 degreeswhen projected orthogonally onto the plane.

Paragraph 32. The guide of any of paragraphs 22 to 30, wherein the rodand the indicator form an angle between one another of 79 to 83 degreeswhen projected orthogonally onto the plane.

Paragraph 33. The guide of any of paragraphs 22 to 32, wherein theindicator is a metallic wire.

Paragraph 34. The guide of any of paragraphs 22 to 33, wherein thecarrier is slidable along the rod parallel to a long axis defined by therod.

Paragraph 35. The guide of any of paragraphs 22 to 34, wherein thecarrier is firmly attached to the rod.

Paragraph 36. The guide of any of paragraphs 22 to 35, the indicatorbeing a central indicator, further comprising a pair of offsetindicators that are offset by the same angle value from the centralindicator when projected orthogonally onto the plane.

Paragraph 37. The guide of paragraph 36, wherein the angle value is 2,5, or 10 degrees.

Paragraph 38. The guide of paragraph 36 or 37, wherein the centralindicator is thicker than each of the offset indicators.

Paragraph 39. The guide of any of paragraphs 22 to 38, wherein each ofthe first and second sides of carrier is marked to indicate which of thesides should face away from a left leg when used for a left leg andwhich of the sides should face away from a right leg when used for aright leg.

Paragraph 40. The guide of paragraph 39, wherein the carrier is markedwith characters on each of the first and second sides to indicate whichof the sides should face away from a left leg when used for a left legand which of the sides should face away from a right leg when used for aright leg.

The disclosure set forth above may encompass multiple distinctinventions with independent utility. Although each of these inventionshas been disclosed in its preferred form(s), the specific embodimentsthereof as disclosed and illustrated herein are not to be considered ina limiting sense, because numerous variations are possible. The subjectmatter of the inventions includes all novel and nonobvious combinationsand subcombinations of the various elements, features, functions, and/orproperties disclosed herein. The following claims particularly point outcertain combinations and subcombinations regarded as novel andnonobvious. Inventions embodied in other combinations andsubcombinations of features, functions, elements, and/or properties maybe claimed in applications claiming priority from this or a relatedapplication. Such claims, whether directed to a different invention orto the same invention, and whether broader, narrower, equal, ordifferent in scope to the original claims, also are regarded as includedwithin the subject matter of the inventions of the present disclosure.Further, ordinal indicators, such as first, second, or third, foridentified elements are used to distinguish between the elements, and donot indicate a particular position or order of such elements, unlessotherwise specifically stated.

We claim:
 1. A method of bone alignment under fluoroscopic imaging, themethod comprising: selecting a guide including a radiopaque axialmember, a radiolucent carrier, and a radiopaque indicator held by thecarrier and elongated along an indicator axis, wherein the axial memberand the indicator are parallel to the same plane and form an anglebetween one another of less than 90 degrees when projected orthogonallyonto the plane, and wherein the carrier has a first side and a secondside opposite one another; and aligning the axial member with an axisdefined by one or more bones of a leg, and the indicator axis with aknee joint of the leg, in an anterior-posterior, fluoroscopic view ofthe leg; wherein the first side of the carrier faces the knee joint ifthe leg is a left leg, and the second side of the carrier faces the kneejoint if the leg is a right leg.
 2. The method of claim 1, wherein theaxial member and the indicator form an angle between one another of 79to 88 degrees when projected orthogonally onto the plane.
 3. The methodof claim 1, wherein the indicator is a central indicator, wherein thestep of selecting a guide includes a step of selecting a guide having apair of radiopaque offset indicators, and wherein the offset indicatorsare offset in opposite rotational directions from the central indicatorwhen the central indicator and the offset indicators are projectedorthogonally onto the plane.
 4. The method of claim 3, wherein each ofthe offset indicators is offset by an integral number of degrees fromthe central indicator when the central indicator and the offsetindicators are projected orthogonally onto the plane.
 5. The method ofclaim 1, wherein the step of selecting a guide includes a step ofselecting a guide having one or more radiopaque skew indicators held bythe carrier, and wherein each skew indicator defines a long axis that isorthogonal to the plane.
 6. The method of claim 1, wherein the step ofselecting a guide includes a step of selecting a guide having theindicator substantially enclosed by the carrier.
 7. The method of claim1, wherein the step of selecting a guide includes a step of selecting aguide in which the first side and the second side of the carrier areparallel to the plane.
 8. The method of claim 1, wherein the step ofselecting a guide includes a step of selecting a guide havingorientation indicia indicating that the second side of the carriershould face away from the knee joint when the guide is used for a leftleg, and that the first side of the carrier should face away from theknee joint when the guide is used for a right leg.
 9. The method ofclaim 1, wherein the step of aligning includes a step of moving piecesof a femur or tibia relative to one another.
 10. The method of claim 1,wherein the knee joint is natural or at least partially prosthetic. 11.The method of claim 1, wherein the step of aligning includes a step ofaligning the indicator axis with a line defined by a femoral portion ora tibial portion of the knee joint in the anterior-posterior,fluoroscopic view of the leg.
 12. The method of claim 1, wherein theaxis is an anatomic axis defined by the femur or tibia of the leg, or isa mechanical axis defined by the femur and the tibia.
 13. The method ofclaim 1, further comprising a step of selecting one of the first andsecond sides of the carrier to face the knee joint based on whether theleg is a left leg or a right leg, wherein the step of selecting one ofthe first and second sides is based on orientation indicia presented bythe guide, and wherein the orientation indicia include a plurality ofcharacters.
 14. A method of bone alignment under fluoroscopic imaging,the method comprising: selecting a guide including a radiopaque axialmember, a radiolucent carrier, and a radiopaque indicator held by thecarrier, the axial member having opposite ends and being elongated alonga linear axis between the opposite ends, the radiolucent carrier beinglocated at one of the opposite ends or along the axial member betweenthe opposite ends, wherein the axial member and the indicator areparallel to the same plane and form an angle between one another of lessthan 90 degrees when projected orthogonally onto the plane, and whereinthe carrier has a first side and a second side opposite one another; andaligning the axial member with an axis defined by one or more bones of aleg, and the indicator with a joint of the leg, in ananterior-posterior, fluoroscopic view of the leg; wherein the first sideof the carrier faces the joint if the leg is a left leg, and the secondside of the carrier faces the joint if the leg is a right leg.
 15. Amethod of bone alignment under fluoroscopic imaging, the methodcomprising: selecting a guide including a radiopaque axial member, aradiolucent carrier, and a radiopaque indicator held by the carrier,wherein the axial member and the indicator are parallel to the sameplane and form an angle between one another of less than 90 degrees whenprojected orthogonally onto the plane, and wherein the carrier iselongated transverse to the axial member and has a first side and asecond side opposite one another; and aligning the axial member with anaxis defined by one or more bones of a leg, and the indicator with ajoint of the leg, in an anterior-posterior, fluoroscopic view of theleg; wherein the first side of the carrier faces the joint if the leg isa left leg, and the second side of the carrier faces the joint if theleg is a right leg.